Directional instrument



July 2, 1940. P. KOLLSMAlfI 2,206,505 DIRECTIONAL ms'mmn-m Filed July 7, 1938 4 Sheets-Sheet 1 I I 49 I a; '1 m fin." 50

P. KQLLSMAN x 22,506

DIRECTIONAL INSTRUMENT Filed Jyzly 7, 1938 4 Sheets-Sheet 2 iml.a. 5

P. KQLLSMAN 2,206,506

DIRECTIONAL INSTRUMENT Filed July 7, 19ss z 4 Sheets-Shet 4,

Patented July 2, 1 940 oT-Ficr:

nmnc'rromr. ms'musmnr Paui Koilsman, Stamford, Conn, assignor, by

mesne assignments,

Detroit, Mlch., a corporation Mi to Square D Company;

Application July 7, 1938, semi 1m mm 70laims.

This invention relates to improvements in directional instruments, more particularly to directional instruments for determining the di-- rection of travel of movable craft.

Among other objects this invention aims. to provide an improved directional instrument,

, more particularly a magnetic compass, having a substantially vertical dial andbeing so con-- structed as to permit mounting oi the instrul. ment on an instrument panel or other fixed part of an airplane orspeedboat with the dial in a fixed substantially vertical position without the necessity of employing the conventional gimbal mounting commonly used for suspending comll passes. It is an object of this invention, accordingly, to provide an improved directional instrument which can be rigidly mounted on a fixed part of the. craft in a similar manner as other control instruments, such as pressure 20 gages, speedometers, temperature indicators, and

the like,

' It is a further objectaf this invention to provide in a magnetic. compass a directional magneticelement mounted for freedom to turn about.

25 and tilt relatively to, a substantially vertical axis, together with means for actuating an indicator in true response to the magnetic north-south direction to which the magnetic element responds. v

More specifically, this invention aims at providing in a magnetic compass in combination with a directional magnetic element an improved magnetic pick-ofi actuated'through magnetic confinement by the directional element and as transmitting directional movements to an indicator, the magnetic pick-oil being so con-- strucied that no error will be introduced into the directional indication even upon relatively-large tilting of the compass casing.

40 It is a iurther object oi this invention to provide in a directional instrument, operating on any of the various well-known principles oi directional indication, improved indicating means,

permitting steering of a predetermined course 1 45 as well as permitting a precise determinationor deviations from said predetermined course.

Further aims, objects and advantagesoi this invention will appear from. a consideration of. the description, which follows with the accompanying drawings, showing for purely illustrative purposes an embodiment of this invention.

It is to be understood, "however, thatthe description is not to be taken iiia limiting sense. the

scope of this invention. being as pended claims.

defined in the ap- Referring to the drawings:

Figure 1 is a front elevation of an improved compass according to this'invention.

Figure 2 is a sectional side elevation of the instrument shown in taken on line-.2- -2.

Figure 3 is a sectional front elevation on a reducedscale, a section being taken on line 3-4 ciIFigure 2. F

Figure 4 isa sectional front elevation of the instrument shown in Figure 2, a section being taken on line 4-4. V v I Figure 5 is a diagram illustrating tion of the magnetic pick-oft.

Figure 6 is a perspective illustration of an improved directional element in combination with a positional pick-oil according to this invention.

An instrument casingis shown in the illustrated embodiment as consisting of a front part I0 and a rear part II, the front part being provided with a flange l2 tor fixedly mounting the instrument on an instrument panel in' a conventional manner, mounting screws it being shown for this purpose. The instrument thusas partakes oi'all movements of the craft about the three principal axes, a vertical or azimuth axis, a longitudinal and a lateral axis. I The front ,part II is provided with extensions l4 and I5 serving as asupport for the direction responsive element. I

In the form of the invention, shown in the drawings and illustrating a magnetic compass, the direction responsive element comprises a first or directionalmagnetic element It mounted within a float H, the float being provided with a pivot is resting in a cup-shaped jewel bearing 1 ID. The Jewel bearing 'is mounted in an upper receptacle or a "supporting stem 20 slidable in a sleeve 2 I. and mountedon the supporting bracket ll. 'A helical spring 2!, bearing against the receptacle oi the stem 2, resiliently supports the float thus preventing possible damage to thedelicate jewel bearing in cases of shock exerted on the' instrument. The directional element is thus supported for; ireedom to turn about as well as tilt relatively to the vertical or azimuth axis I-l. A tubular extension 23, extending into the float i1 and fitting loosely around the cup-shaped receptacle for the jewel bearing It, prevents a disengagement of the pivot and'iewel in cases where tbe'instrument is turned upmde down.

1 A liquid tight chamber 24,-containing a fluidthe opera- Figure 1 9. section being I encloses the float IL the fiuid thus buoyantly u element l8 exerted on the jewel bearing.

A conventional expansion chamber, shown in the illustrated embodiment as being a diaphragm box 26', may be provided to compensate for expansion and contraction of the fluid in response tochanges in temperature. I

For the purpose of deriving a directional impulse from the fluid-enclosed directional ele- 4 ment for actuating indicating means a posicraft or the instrument casing.

tional pick-oft is provided.

In the illustrated embodiment the positional pick-off comprises a second magnetic or follower element 21 mounted on shaft 28, the shaft being rotatable in bearings 29 and 30, supporting.

the follower magnet 21 for freedom to turn about the azimuth axis 5.

The indicating means of the illustrated form of instrument include a pointer 3| supported on a shaft 32 rotatable in bearings 33 and 34 for rotary movement relatively to a normally fixed dial 35, provided with a directional graduation 36. The pointer and dial are visible through a front window 31 of the instrument casing, the

front window of the illustrated instrument being also used forilluminating the dial by means of 'an electric bulb enclosed in. a compartment 38,

as disclosed more specifically in my Patent #2,088,559, dated July 27, 1937.

A bevel gear 39 is secured to the shaft 32 meshing with a second bevel gear 40 on the vertical shaft 28.

The operation of the instrument, so far described, is as follows:

The directional magnetic element, supported for free movement in azimuth, will align itself with the direction of the earths magnetic field by virtue of its confinement by the same. The pivotal support of the directional element permits the element to maintain a horizontal position irrespective of tilting movements of the The second magnetic or follower element 21, being of much smaller magnetic force than the directional element I6, is maintained in magnetic confinement by the same and tends to align itself withthe directional element, thus repeating the movements of the latter in azimuth. The movements of the follower element 21 are transmitted to the indicating means which thus give an indication of the magnetic north-south direction with respect to the direction of travel of the craft on which the instrument is mounted.

In order to permit steering of a predetermined course without the necessity of reading the pointer 3! against the graduation on the dial, a reference member is provided cooperating with the pointer as well as the dial.

In the illustrated form of the invention an externally toothed ring 4! is rotatably supported within the front part III of the instrument casing. The ring 4| bears a reference mark 42 normally cooperating with the pointer and bearing one or several reference lines suitably formed by wires 4! and 44 extending across the face of the dial. The ring 4i is adjustable coaxially with respect to the pointer by means of a knob 45 turning a gear 46 by means of a shaft 41, the gear meshing with the teeth of the ring 4|.

The, operation and use of the reference means is, as follows: 1

Assuming a course of degrees is to be maintained by the pilot of the craft, the reference mark 42 is moved into the respective position 2,206,508 supporting the float with the magnetic element,

relatively to the dial, as shown in Figure 3, by turning the knob 45. The craft is then steered in such manner as to maintain the tip of the pointer 3| opposite the'reference mark 42. In

order to relieve the pilot from unnecessary eyestrain, naturally involved in observing the movements of the pointer'relatively to a point of the graduation or a relatively small reference mark, the reference lines 43 and 44 are provided indicating the maintenance of the proper course by parallelism with the pointer 3|. If a deviation from the predetermined course occurs, the amount of deviation can be easily read on the dial without readjustment into a new position of i the reference mark and lines. When it is necessary temporarily to steer a course different from the set course, for example, in the vicinity of an airport, the temporary new course can be easily steered by maintaining the pointer on the respective graduation mark of the dial in a similar manner as heretofore the dial of a compass was read with respect to a lubbers mark.

It is a feature of this invention that noresetting of the reference means is required in cases where a predetermined course is to be steered temporarily different from the course set at the dial.

The usual magnetic compensator, shown in the illustrated embodiment as enclosed within a box 48-, may be provided to compensate the directional element against local sources of magnetic disturbance. The magnetic compensator 48 may be of any conventional form and is shown in the drawings as being adjustable from the outside by 1 means of screw-headed shafts 49 and 50 actuating adjustment shafts 5| and 52 over gear trains 53 and 54.

In order to insure a correct positional indication under operating conditions where relatively large inclinations of the instrument casing occur, the use of an improved system of directional and follower magnets may be used. The improved form of magnet system is diagrammatically shown in Figure 6.

In Figure 5 it is attempted to illustrate the conditions under which a directional element D and a follower element F operate when an inclination of the axis of rotation 5 of the follower magnet occurs with respect to the true vertical direction. The poles of the magnets are designated in the drawings by letters N and S Inclinations occur, for example, when the craft is inclined about the longitudinal or lateral axis while the directional element maintains a horizontal position due to its pivotal mounting.

In Figure 5 the vertical axis of the instrument casing is represented by numerals 55. I represents the plane of rotation of a follower magnet F shown in this figure as being of rod form. Two further planes II and III normal to each other and to the plane I intersecting are indicated in order to make apparent the movements of the two magnets D and F in space.

Assuming, first, that the axis 55 of the instrument casing be maintained truly vertical, it appears that upon turning of the craft in azimuth the magnet D will turn in a plane parallel to the plane I, and the follower magnet F will accurately repeat the movements of the directional magnet D, maintaining a north-south direction.-

Assuming that the craft be inclined in a northsouth vertical plane, such condition existing, for example, when an airplane ascends or descends while maintaining a north course, it appears that a relative inclination will occur between the diplained, is not the north-south .vertical plane, it

. inclination will be, for example, that the south pole of the directional magnet approaches the north pole of the follower magnet F while the opposite poles are spaced farther apart. j It is apparent that such inclination will not aflect the accuracy of the directional position of the follower magnet.

Assuming that in a second case a similar inclination occurs while the craft is maintaining a a west or east course while being inclined about its lateral axis, such condition existing, for example, during an ascent or descent of a plane maintaining a west or east course, it will become apparent that no inclination between the directional and follower magnets occurs; Accordingly, the indication of an indicator operated by the follower magnet will be curate.

assuming, finally, that the craft be inclined about its lateral axis while steering a course other than a north, south, east or west course, adeflection of both the directional as well as fol- J lower magnets will occur as will be apparent from the following:

It may be assumed that an inclination occurs between the horizontal. planeof the directional magnet D and the plane of rotation of the. 161;.

lower magnet F and that the inclination besuch that the south pole of the inclined towards the plane apparent that on account of the reduced .distance between the south pole of the magnet, designated in this position as D, and the plane I the directional magnet will more strongly ,attract the north pole of the follower magnet. As: suming at this moment that the earth magnetic field were not present, it appears that the direct-. tional magnet-D as well as the follower it ti' inwhich'thesou; F will move n o a posi on 7 ma atera ly Extended pole of the directional magnet is closest to the north pole of the follower m net. In' other words, the two magnets will come to rest in the lane in which the inclination has occurred. As p Y tion-by'th'e proximate part of; the magnetic field this plane of inclination, as liereinbeforeexwill be understood that, inasmuch as actually the earth magnetic field acts on both the directional as well as the follower magnet, the earth magnetic field will tend to move both magnets out of the alignment with the plane of inclination.

- 5 Apparently, in this condition'neither the directional magnet nor the follower magnet will .be aligned with the earth magnetic field and, .ac

cordingly,'will not provide a correct directional impulse for actuating an indicator.

In order to overcomethis inclination error", as it may be called, an improved system of directional andfollower elements is employed according to this invention,- The principle .of the compensation for the inclination ermrds briefly the following: a

.When, due to an inclination, the

magnet is deflected from the true north-south;

direction, a shift in the 'azimuthor phase-relation between thedirectional and the follower magnets is provided for, the. phase shift being approximately equal to the deviation error of-the directional magnet. This result'is accomplished in the following manner;

In the improved magnetic compass a directional or 'firstmagnetic element is provided mounted for freedom to turn about, and tilt relameans of a pivot It embodiment as to provideama'gnetic field of greater horizontal directioligil magnet be' I. It, cm'seasily- 9 e shaft 2: in bearings 29 and :0.

cc! the inclination 3 tively-to, a substantially magnetic or follower element is provided mounted for free movement about the said vertical axis in confinement by the first magnetic or directional element. The magnetic elements are made of unequal magnetic strength in order to make the combination responsive to the action of the earth magnetic field, and at least one of. the magnetic elements to set up a magnetic field which is of substantially greater horizontal width than vertical depth. is accomplished by providing the element with a horizontally extended pole area. As will be hereinafter more fully described, a single magnet may be so shapedas to have a laterally extended. pole face, or a similar effect. beproduced by using-a pair of magnets having their poles horizontally spaced.

In Figure 8 the directional magnetic element is own'as being of elongated,more'particularly octagonal, shape, .tapered towards the poles, thus setting up a magnetic field obviouslyof greater extension horizontally than vertically. The directional magnetic element is shown as being mounted for tilting and turning movement by resting in a cup IS. A follower element is show in the illustrated likewise being of such structure as width than vertical depth, the follower magnet being. formed by two horizontally spaced .magnets 2|.' and 21-" preferably shorter than the directional magnet l,6'- and rotatable with a magnets 21' land 21", constituting the follower member, are arranged with their poles spaced'farther apart than the width of the pole area offthe directional element. The operation of thisimproved form of magnetic system is, as follows;

an inclination occurs, which would cause the h'ereinbefo're: explained inclination error, system is moved closer, to the magnetic field up by the other magnetic system. The latter system will now'be strongly governed in its direcof the first element and, accordingly, assume a diii'erent' phase relation with respect to the first is made of such structure as upon a tilt of the direcvertical axis. A second The indifield of the one magnetic pole of the directional magnet will now act'strongest upon the closest pole of the shorter follower magnet-org-in other words, locally on the one side of-the horizontally extending pole area of the follower element thus causing a change in the relative azimuthal or phase relationto canerror. By choosing the proper relation between the magnetic power ofthe first and the second made equal to 4 to the particular embodiments he ein shown and element, this phase shift can be, e deviation of the directional. element from the magnetic north-south direcdescribed. More particularly, the improved form of indicator is not limited to the use in connection with a magnetic element for its actuation, but may be combined with any of the wellknown direction maintaining devices used in navigation. It is further notindispensablethatall the features of this invention be used conjointly since they may advantageously be employed in various combinations and sub-combinations.

What is claimed is:

1. In a magnetic compass the combination of a support; a direction magnetic element in the shape of an elongated octagon mounted on said support for freedom to turn about, and tilt relatively to, a substantially vertical axis; a follower member mounted on said support for free movement about said axis, said follower member including two horizontally spaced substantially parallel follower magnets in magnetic confinement by said element; and direction indicating means connected to be moved by said follower member in response to movements of said member about the said axis, whereby said indicating means will be actuated in response to movements of said element in azimuth, unaffected by tilting movements of said support.

2. In a magnetic compass the combination of a first magnetic element having pole faces; a second magnetic element shorter than and magnetically coupled with said first element and having pole faces wider than the first element; means for mounting one of said elements for turning about and tilting relatively to a substantially vertical axis; means for mounting the other of said elements for turning about a substantially vertical axis coaxial with said one element; and indicating means connected to be operated by said other element.

3. In a magnetic compass the combination of a first magnetic element; a second magnetic element including a pair of permanent magnets shorter than, and magnetically coupled with,

said first magnetic element, the poles of the pair of magnets being spaced wider apart horizon- .tally than the width of the pole faces of said first element; means for mounting one of said elements for turning about and tilting relatively to a substantially vertical axis; means for mounting the other of said elements for turning about a substantially vertical axis'coaxial with said one element; and indicating means connected to be operated by said other element.

'4. In a magnetic compass-a the combination with a support, of a first magnetic element; a second magnetic element longer than and magnetically coupled with said first elementv and having pole faces narrower than the pole faces of the first element; means for mounting one of said elements on said support for turning about and tilting relatively to a substantially vertical axis; means for mounting the other of said elements on said support for turning about a substantially vertical axis coaxial with said one element; and indicating means connected to be operated by said other element, whereby upon tilt of said support in a direction other than the magnetic north-south or east-west direction a deviation of the other element from the magnetic north-south direction resulting from such tilt will be counteracted by a change in the phase relation between the two elements.

5. In a magnetic compass the combination with a support, of a first magnetic element;' a

second magnetic element including a pair of permanent magnets shorter than, and magnetically coupled with, said first magnetic element, the poles of the pair of magnets being spaced wider apart horizontally than the width of the pole faces of said first element; means for mounting one of said elements on said support for turning about and tilting relatively to a substantially vertical axis; means for mounting the other of said elements on said support for turning about a substantially vertical axis coaxial with said one element; and indicating means connected to be operated by said other element. whereby upon tilt of said support in a direction other than the magnetic north-south or eastwest direction a deviation of the other element from the magnetic north-south direction resulting from such tilt will be counteracted by a change in the phase relation between the two elements.

6. In an indicating instrument a dial bearing a graduation; a pointer movable about a fixed axis and readable on the graduation of said dial; and a reference member adjustable relatively to said pointer and said dial and bearing an index freadable on the graduation of said dial, said reference member bearing two parallel reference lines disposed one at each side of the pointer cooperating with said pointer for indicating maintenance of a predetermined indication by parallelism with said pointer. I

7. The combination of an instrument casing; a substantially vertical pivot fixed in said casing; a directional magnet mounted on said pivot for freedom to turn and tilt relatively to said casing; a follower magnet in magnetic confinement by said directional magnet and mounted in said casing for movement coaxially to said pivot, the follower magnet being shorter than the directional magnet but wider at its poles than the directional magnet; and indicating means connected to be actuated by a relative movement of said follower magnet and said casing, whereby a correct directionalindication is obtained irrespective of tilting movements of said directional magnet relatively to said casing.

' PAUL KOLLSMAN. 

